Recently there has been an increased demand for energy saving which is accompanied by employment of measures for decreasing the fixation temperature of toners upon image formation. One of those measures is the use of polyester resins having a low softening temperature in order to further decrease the fixation temperature. However, because of the low softening temperature, toner particles may be melt-adhered to cause blocking during stationary standing thereof such as during storage and transportation.
In order to achieve both blocking resistance and low-temperature fixability, techniques have been proposed in which crystalline polyester resins are used having sharp melt property such that the viscosity is significantly decreased at above the melting point (Patent Literatures 1 to 3).